The Expedition

A Constellation of Observations

MOSAiC observations will be specifically designed to characterize the important processes within the atmosphere-ice-ocean system that impact the sea-ice mass and energy budgets. These include heat, moisture, and momentum fluxes in the atmosphere and ocean, water vapor, clouds and aerosols, biogeochemical cycles in the ocean and ice, and many others.

The centerpiece of the observatory will be a manned, ship-based ice camp with comprehensive instrumentation to thoroughly observe processes within the atmosphere, ice, and ocean. This central, intensive observatory will be embedded within a constellation of distributed measurements made by buoys, ice-tethered profilers, remote stations, underwater drifters, unmanned aerial systems, aircraft, additional ships, and satellites. These distributed observations will provide critical information on the spatial context and variability of key parameters, and allow for limited measurements in environments with sea-ice of differing age, thickness, and concentration.

Preliminary Drift Trajectory Plan

The MOSAiC Observatory will be deployed in, and drift with, the Arctic sea-ice pack for a full annual cycle, starting in september 2019. The specific location of the start of the drift will be selected such, that the observatory will drift towards the North Pole and to the Fram Strait, using the natural transpolar drift of the sea ice. By drifting with the ice in a "sea-ice Lagrangian" sense, MOSAiC will observe the atmospheric and oceanic processes that affect the sea-ice as it evolves from new first year ice to multi-year ice and eventually towards the decay stage as the ice approaches the North Atlantic sector. As such, MOSAiC will observe the full annual cycle of the sea ice.

Potential drift trajectory of the Polarstern for the selected starting position at 120° E and 84° N. Colors represent the month of the drift starting in October 2019 and ending in October 2020. The small color bar illustrates the sea ice concentration o (Photo: Alfred-Wegener-Institut)

A Model Testbed

To understand, explain, and project changes in the Arctic climate system, models will be used synergistically with observations. Observations are critical to understand the key climate processes in the Arctic and for evaluating and developing valid model representations for these.

Climate models studies will integrate the complex collections of physical processes into a consistent framework that will be used to weather forcast, sea-ice predictions, and climate projections. Models provide perspectives on scale, teleconnections, and feedbacks that are not accessible to direct observation. uating and developing valid model representations for these.

MOSAiC observations will serve as a testbed for models at many scales, providing the constraints that are needed to improve process-based model parameterizations for Arctic climate processes. High resolution process models will be used for detailed studies, and serve as a basis for regional climate model improvements. These studies will feed into the development of the next generation global climate models which will then include a realistic representation of Arctic processes. uating and developing valid model representations for these.

Model guidance is critical for the basic design of MOSAiC, by identifying specific processes that contribute to model uncertainty and guiding the deployment of observational assets. Additionally, regional modeling activities will aim to address important questions regarding the role of the Arctic as a global energy sink, the manner in which global teleconnection patterns are affected by a changing Arctic ice pack, and the impacts these changes have on lower-latitude circulation and weather.

MOSAiC modeling and observational activities will be closely linked with international modeling efforts organized by the World Weather Research Program and World Climate Research Program, such as the Year of Polar Prediction.